Node.js+Express搭建FHIR Server时POST请求体接收为Undefined问题

我用Node.js和Express搭建FHIR Server，尝试通过POST请求创建Patient资源，但服务器始终收到undefined的请求体，换用Thunder Client和VS Code REST Client测试都存在这个问题。已做的排查包括：

• 确认JSON请求体格式正确，包含resourceType等必填字段
• 客户端Content-Type、Accept头已设为application/fhir+json
• 验证请求方法为POST、端点URL与路由匹配
• 排查客户端设置、重启服务器、查看日志均未发现异常

核心原因 #

Express默认不会自动解析请求体，且默认的express.json()中间件仅处理application/json类型的请求，而FHIR请求使用的是application/fhir+json类型，导致请求体未被解析，所以req.body为undefined。

解决方案 #

在Express应用中添加带类型配置的express.json()中间件，确保能解析application/fhir+json格式的请求体，且中间件要挂载在所有路由定义之前。

修改后的核心代码 #

const { VERSIONS } = constants;
const express = require('express');

let config = {
  profiles: {
    patient: {
      service: './patient.service.js',
      versions: [VERSIONS['4_0_0']],
    },
  },
};

let server = initialize(config);
let logger = loggers.get('default');

// Create an Express application
const app = express();

// 关键：添加解析application/fhir+json和application/json的中间件，放在路由之前
app.use(express.json({
  type: ['application/json', 'application/fhir+json']
}));

// In-memory data store for Patient resources
const patientDataStore = [];

// creating a Patient resource
app.post('/4_0_0/Patient', (req, res) => {
    console.log('Received POST request with data:', req.body);
    console.log('Request headers:', req.headers);
  const patientData = req.body;

  console.log('Received POST request with data:', patientData);

  // Perform validation, data storage, etc.
  // For simplicity, we'll just push the patientData to the in-memory store
  patientDataStore.push(patientData);
  console.log('Patient data stored:', patientDataStore);
  // Send a response indicating success (HTTP status code 201 for resource creation)
  res.status(201).json({ message: 'Patient resource created successfully' });
});

// 其余路由和代码保持不变
app.get('/4_0_0/', (req, res) => {
    res.send('GET request to /4_0_0/');
});

app.get('/4_0_0/Patient', (req, res) => {
    console.log('Data in patientDataStore:', patientDataStore);
    res.json(patientDataStore);
});

app.get('/patientData', (req, res) => {
    console.log('GET request to /patientData');
    console.log('Data in patientDataStore:', patientDataStore);
    res.json(patientDataStore);
});

const fhirMiddleware = (req, res, next) => {
  server(req, res, next);
};

app.use('/fhir', fhirMiddleware);

const PORT = 3000;

app.listen(PORT, () => {
  logger.info(`Starting the FHIR Server at localhost:${PORT}`);
});

注意事项 #

• 中间件的挂载顺序至关重要，必须在所有路由定义之前添加，否则路由处理时请求体还未被解析
• 如果后续还有其他类型的请求体需要解析（比如form-data），可以额外添加express.urlencoded()等对应的中间件

内容的提问来源于stack exchange，提问作者legacyunlimited